Assessing the Lifecycle Sustainability Costs and Benefits of Seismic Mitigation Designs for Buildings

A complete sustainable-performance analysis that takes into consideration the whole of the triple bottom line of sustainability is necessary when one needs to balance social, economic, and environmental impacts in an optimal cost-effective design based fundamentally on sustainability performance objectives. This study introduces a methodology that can translate seismic building damage into clearly quantifiable social, economic, and environmental impacts, which can be used when selecting repair methods appropriate for various states of building damage and for the local economic and environmental situation. The authors also propose a lifecycle-assessment framework with which one can evaluate the costs and benefits associated with a seismic design over the lifecycle of a building. Two case studies are presented. The first case assesses the sustainability performance of a single RC building under seismic risk. The second case, taking into account the uncertainty associated with seismic events, comprises a risk-based cost-benefit analysis of the desirability, in terms of the three sustainability metrics (separately and in combination), of two seismic retrofit designs on a regional scale. A comparison of the relative merits of the two proposed retrofit designs revealed that preventing buildings from becoming irreparably damaged plays an important role in increasing the cost-efficiency of a retrofit design. These findings also indicate that, although neither design can be considered feasible with respect to the three sustainability metrics individually, the lower-cost/lower-resistance design is justifiable if measured by the combined benefit from all three metrics, expressed in monetary terms. This finding emphasizes the necessity of a complete sustainable-performance analysis for achieving a cost-effective design. Finally, when comparing all three metrics in monetary terms, the savings associated with the reduction in fatalities contribute the most to the total expected benefit of a retrofit project, followed by reduced repair costs and reduced CO2emissions.